Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.Nghiên cứu quá trình xử lý nitơ trong nước thải sinh hoạt bằng quá trình Anammox sử dụng giá thể vi sinh cố định.
1 MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF CIVIL ENGINEERING NGUYEN THI MY HANH STUDY ON NITROGEN TREATMENT IN DOMESTIC WASTEWATER BY ANAMMOX PROCESS USING FIXED BED BIOMASS CARRIER Specialization: Environmental Technology for Water and Wastewater Code: 9520320-2 SUMMARY OF DISSERTATION Ha Noi, 2022 The dissertation was completed at Hanoi University of Civil Engineering Scientific Advisor: Assoc.Prof PhD Tran Thi Hien Hoa Reviewer 1: Assoc.Prof PhD Nguyen Manh Khai Reviewer 2: Assoc.Prof PhD Hoang Thi Thu Huong Reviewer 3: Assoc.Prof PhD Doan Thu Ha The dissertation will be defended before the University Committee at Hanoi University of Civil Engineering At hour day .month 2022 The dissertation can be found at the libraries: - Hanoi University of Civil Engineering - The National Library INTRODUCTION Research rationale By 2035, the population of Vietnam will be about 106.3 million, including 47.87 million urban residents (44.87% of the population) and wastewater quantity of urban which needs to be treated is 7.63 million m3 per day Up to now, there have been about 70 concentrated wastewater treatment plants in urban areas However, there are only three wastewater treatment plants with separated drainage systems Septic tanks, which are used by more than 90% of households, play an important role in the preliminary treatment of domestic wastewater in concentrated drainage systems Domestic wastewater is formed during human activities, which contains suspended solids, organic substances, microorganisms, and nutrients that need to be treated before being discharged into the wastewater receiving sources With wastewater treatment technologies being applied in Vietnam, some cannot thoroughly treat nitrogen compounds, such as trickling biological filters or traditional activated sludge technology (CAS) Others, such as AO, A2O, and SBR, based on the nitrification/denitrification process, also require internal sludge circulation or supply large amounts of gas or additional external carbon sources Based on the theoretical basis of nitrogenous compounds treatment by anaerobic oxidation, it is found that the Anammox process has advantages such as no need to add an external carbon source, saving energy for aeration, and producing a negligible amount of sludge, reducing greenhouse gas emissions, and saving construction area Therefore, nitrogen treatment technology by the Anammox process is considered environmentally friendly and seems to be very suitable for bringing wastewater treatment technology of Vietnam closely to the development trend of the world's "sustainable development" To apply the Anammox process to practical domestic wastewater treatment, it is necessary to research the operating parameters, reaction techniques, and factors affecting the efficiency of the treatment process The biomass carrier plays a vital role in supporting the microbial adhesion process in the wastewater treatment system Because Felibendy material has a tough, durable, fibrous structure, porous, light, large surface area, and high absorbency, it meets the requirements for adhesion bacteria Felibendy was selected as a fixed bed biomass carrier in the experimental reactor in this research The "Research on nitrogen treatment in domestic wastewater by Anammox process using fixed bed biomass carrier" is necessary to gradually put the Anammox process into the practical application of nitrogen treatment in domestic wastewater in Vietnam Research objectives - To evaluate the possibility of using Felibendy as a fixed bed biomass carrier by assessing the nitrogen removal efficiency of the Anammox process in the AX reactor - To evaluate the ability to remove nitrogen in real domestic wastewater by partial nitrification and Anammox process with Felibendy as fixed bed biomass carrier - To evaluate the influence of organic matter in wastewater (via COD parameter) on the efficiency of nitrogen treatment by the Anammox process Determine the kinetic parameters of the Anammox process with different C/N ratios in wastewater Object and scope of the study Subjects: - Anammox process with fixed bed reaction technique - Inorganic nitrogen containing compounds in domestic wastewater - Domestic wastewater (synthetics wastewater and real wastewater from the effluent of septic tank of the dormitory of Hanoi University of Civil Engineering are the subject of a case study) Scope The research was conducted for domestic wastewater in urban areas of Vietnam on PN and AX reactors using Felibendy fixed bed biomass carrier on laboratory scale reactors Scientific basis - Treatment of nitrogenous compounds in domestic wastewater using Anammox technology based on partial nitrification and the Anammox process The first process is partial nitrification which uses Nitrosomonas bacteria to oxidize ammonium to nitrite partially In the following process (Anammox), ammonium is oxidized under anaerobic conditions with nitrite as an electron acceptor and forms N2 with the participation of autotrophic bacteria Planctomycetes - Based on the principle of microbial growth and adhesion, using a fixed bed biomass carrier in the treatment process increases the bacterial density on the surface and enhances the treatment efficiency - Based on the equations of the basic kinetic model (first order, Graus and Stover Kincannon model), which has been based on the biological metabolism of substances in wastewater Research content The dissertation is conducted with the following contents: - Literature review of nitrogen treatment technology in domestic wastewater, literature review of Anammox process in the world and Vietnam, literature review of biomass carrier used in Anammox process - Research on the scientific basis for nitrogen treatment applying partial nitrification and the Anammox process - Experimental research in the laboratory with PN and AX reactor - Evaluate and discuss the results of the research Methodology The dissertation uses the basic methods: - Method of literature review - Inheritance result method - Experimental research method - Methods of synthesis and analysis - Statistical and data processing method - Method of comparison and contraction - Method of expert opinion New contributions of dissertation - Determine the suitable hydraulic retention time for PN and AX reactor using fixed bed biomass carrier Felibendy to treat nitrogenous compounds in domestic wastewater: hours for PN reactor and 6h for the AX reactor - Determined the inhibitory threshold for Anammox process in the AX model by the organic matter content (COD) of 300 mg/L - Determine the maximum consumption rate constant U max and saturation constant KB of the Stover Kincannon kinetic model for Anammox process corresponding to different C/N ratios Scientific and practical significance of the dissertation Scientific significance - The research has determined the suitable hydraulic retention time (HRT) in the PN and AX reactor using Felibendy as fixed bed biomass carrier - The research has evaluated the effect of organic matter in wastewater on the Anammox process (COD > 300 mg/L inhibits Anammox process) - The research has determined that the Stover Kincannon model is suitable to describe the kinetics of the Anammox process The kinetic parameters Umax and KB of the Stover Kincannon model with different C/N ratios were also determined Practical significance - The hydraulic retention time determined in the study (9h for the PN model and 6h for the AX model) is one of the parameters serving the design of nitrogen treatment works applying the partial nitrification process and Anammox process - The kinetic parameters Umax and KB of the Stover Kincannon model can be used to predict the effluent and the efficiency of the treatment process Thesis structure The thesis structure includes: Introduction Chapter 1: Literature review of issues related to nitrogen treatment in domestic wastewater Chapter 2: Scientific basis of the nitrogen treatment process with partial nitrification and Anammox process Chapter 3: Methodology Chapter 4: Results and discussion Conclusions and recommendations CHAPTER LITERATURE REVIEW OF ISSUE RELATED TO NITROGEN TREATMENT IN DOMESTIC WASTEWATER 1.1 Sources, characteristics of domestic wastewater and the requirement of wastewater receiving sources 1.1.1 Sources, and characteristics of domestic wastewater Domestic wastewater (including two types: black and grey water) is formed during human activities According to TCVN 7957:2008, each person discharges about 60-65 g of suspended solids into the sewerage system, 30-35 g of BOD, and g of ammonium…per day In Vietnam, septic tanks play a significant role, especially in the general drainage systems The anaerobic digestion process in the septic tank significantly reduces the amount of organic matter in the form of carbon but has no effect on nitrogen compounds, even the amount of nitrogen compounds in the effluent of the septic tank is higher than in the influent due to the anaerobic digestion 1.1.2 Forms of nitrogenous compounds in domestic wastewater In domestic wastewater, nitrogen exists in the form of inorganic nitrogen (ammonia/ammonium, nitrite, and nitrate) and organic nitrogen (amino acids, proteins, urea, etc.) Total nitrogen in wastewater (TN), which includes organic nitrogen and inorganic nitrogen, is determined by the formula: + TN = N organic + NH + NO - + NO (1- 1) TN = TKN + NO2- + NO3(1- 2) Under the action of bacteria, nitrogenous compounds, especially proteins and urea, are rapidly hydrolyzed to form ammonium/ammonia The formula determined total inorganic nitrogen (TIN) in wastewater: TIN = NH4+ + NO2- + NO3(1- 3) 1.1.3 The impact of nitrogenous wastewater on public health and the environment Wastewater containing high nitrogen amounts can cause colored water and an unpleasant odor reduction of dissolved oxygen concentration (DO) in water It also causes eutrophication, reduces water quality, produces toxins, and destroys many beneficial organisms in the water… 1.1.4 Regulations of the recieving water source for nitrogenous parameter in domestic wastewater Before being discharged into the receiving source, domestic wastewater must be treated and meet the requirements according to QCVN 14:2008/BTNMT Ammonium and nitrate concentrations in treated domestic wastewater discharged into the type A source is mg/L and 30 mg/L, and into type B sources are 10 mg/L and 50 mg/L, respectively 1.2 Literature review of nitrogen treatment methods 1.2.1 Physical - chemical methods Physical – chemical methods include Stripping, ion exchange 1.2.2 Chemical methods Chemical methods include ammonium oxidation, ammonium precipitation by MAP 1.2.3 Biological methods Biological methods include nitrification/denitrification and Anammox process 1.3 Literature review of nitrogen in wastewater treatment technologies 1.3.1 Nitrogen treatment technologies using nitrification/ denitrification process Nitrogen treatment technologies using nitrification/denitrification process include AO, SBR, AAO, MBR, MBBR, FAST 1.3.2 Nitrogen treatment technologies using Anammox process The application of wastewater treatment technology by the Anammox process is a combination of partial nitrification processes and the Anammox process These two stages can be carried out in two separate reactors (PN/AX) or the same reactor (CANNON, SNAP, OLAND) 1.3.3 Evaluation of of the efficiency of nitrogen treatment technology by nitrification / denitrification process and application technology of Anammox process The Anammox process has the following outstanding advantages compared with the traditional nitrification/denitrification process, · Reducing the use of organic carbon sources · Low sludge production · Savings in the costs of energy consumption · Reducing greenhouse gas emissions However, the Anammox process has not been widely used in practice due to several difficulties, such as the long warm-up and acclimation time of bacteria Besides that, the bacteria are very sensitive to external factors such as temperature, pH, alkalinity, dissolved oxygen, etc 1.3.4 Evaluation of wastewater treatment technologies applied in Vietnam and accessing trends of wastewater treatment technology worldwide Vietnam's urban wastewater treatment technologies are mainly different forms of activated sludge secondary treatment technology such as CAS, SBR, AO, AAO The removal of organic matter and nitrogenous compounds in wastewater needs to be researched and selected to save energy, low carbon emissions, be environmentally friendly, and approach new wastewater treatment technologies worldwide 1.4 Literature review of some nitrogen treatment studies using Anammox process 1.4.1 Literature review of some research on application of Anammox process in the world and in Vietnam The Anammox process was first discovered in the Gist Brocades wastewater treatment plant in the Netherlands in 1995 Since then, the Anammox process has been widely researched with many kinds of wastewater at different scales (laboratory, pilot, and full scale) However, studies on the Anammox process in Vietnam are still limited 1.4.2 Literature review of some carriers using for the Anammox process Many carriers have been studied and applied to the Anammox process, such as PVA gel, MC beads, Bamboo charcoal; PE; nonwoven materials, Felibendy has a tough fibrous structure (the shell is EVOH resin, and the core is PET plastic), which is durable, lightweight, has a large surface area, and is highly absorbent These properties can meet the carrier's requirements and were selected as a fixed microbial substrate to support the Anammox process in the fixed bed reactor 1.4.3 Literature review of studies on the kinetic equations describing the Anammox process Some basic kinetic models are often used, such as the first order model, Monod model, Grau’s model, Contois model, Stover Kincannon model, etc 1.5 Some existing problems when treating nitrogenous compounds in domestic wastewater by the Anammox process and research direction of the dissertation The overview of the remaining issues shows that to gradually put the Anammox process into practically treating nitrogenous compounds in real domestic wastewater in Vietnam, it is necessary to carry out the following tasks: - Evaluate the long-term treatment performance - Determine the appropriate hydraulic retention time in PN/AX reactor using a fixed bed biomass carrier - Determine the threshold of influence of organic matter on the Anammox process - Determine the kinetic parameters of the Anammox process corresponding to different C/N ratios CHAPTER SCIENTIFIC BASIS OF NITROGEN TREATMENT TECHNOLOGY USING PARTIAL NITRITATION AND ANAMMOX PROCESS 2.1 Anammox process 2.1.1 The nature of the Anammox process Anammox process is defined as the process where ammonium and nitrite are oxidized directly to N2 gas under anaerobic conditions with ammonium as an electron donor and nitrite as an electron acceptor to form N2 NH ++1,32NO -+0,066HCO -+0,13H+ → 1,02 N2 + 0,26 NO3- + 0.066 CH2O0,5N0,15 + 2,03 H2O (2.1) The Anammox process was performed with the contribution of the autotrophic group of bacteria Planctomycetes 2.1.2 Biochemistry of the Anammox process The marker isotope method (15N) showed that hydroxylamine and hydrazine are essential mediators in the intracellular metabolism of the Anammox reaction Autotrophic bacteria of the group Planctomycetales carry out an anammox process The bacteria in the Anammox process belong to the following three generas: Candidatus Brocadia, Candidatus Kuenenia, and Candidatus Scalindua 2.1.3 Affecting factors to the Anammox process Anammox process with the participation of Planctomycetes anaerobic bacteria is affected by many factors such as pH, temperature, The operating parameters are maintained as follows DO ≈ mg/L (PN reactor), DO < 0.5 mg/L (AX reactor), and pH in the range 7.07.5; the temperature is kept stable at 33.0 ±1.00C utilizing a thermostat 3.3 The order of conducting experimental research 3.3.1 The first experiment Contents of the experiment Experimental sequence Experimental operating parameters Working principle of the experimental reactor 3.3.2 The second experiment (same as 3.3.1) 3.3.3 The third experiment Fig 3.1 The diagram of (same as 3.3.1) the first experiment Fig The diagram of the second experiment AX1 AX2 Fig 3.3 The diagram of the third experiment 3.4 Sampling method, sample analysis and data processing 3.4.1 Sampling method Inlet and outlet wastewater have collected an average of every 23 days and were analyzed at the laboratory of the Water Supply and Sewerage Department, HUCE 3.4.2 Analytical methods The parameters were measured include pH, DO, COD, NH 4+ N, NO2- -N, NO3- -N Analytical methods were performed according to “Standard methods for the examination of water and wastewater” 3.4.3 Data processing methods The data are processed on Microsoft Excel software 3.4.4 Bacterial strain identification method Using molecular biology techniques, identification by PCR (Polymerase chain reaction) technique 3.4.5 Method of building mathematical equations to determine kinetic parameters of partial nitrification and Anammox process Using Microsoft Excel 2010 software, set up linear equations showing the relationship between parameters of kinematic equations on vertical and horizontal axes CHAPTER RESULTS AND DISCUSSION 4.1 Evaluation of the nitrogen compounds removal efficiency of AX reactor using fixed bed biomass carrier (Felibendy) 4.1.1 Effective removal of ammonium, nitrite, and total nitrogen The changes in the concentration of nitrogen compounds during the periods are shown in Fig 4.1 and Fig 4.2 Fig 4.1 Changes of NH4+-N concentration during periods Fig 4.2 Changes of NO2- -N concentration during periods Fig 4.3 Changes of TN concentration during periods Fig 4.1 Changes of TN removal rate during periods The research was conducted in periods with increasing concentrations of nitrogenous compounds At the beginning of the operation, the bacteria in the AX reactor had not yet been adapted, so the removal efficiency of ammonium, nitrite, and total nitrogen was low, only 40.9%, 35.6%, and 21.3% After 191 days of operation, Planctomycetes bacteria gradually adapted and developed well, so the total nitrogen removal rate increased significantly and reached a maximum of 1.15 kg/m3/day At the end of the 4th period, the AX reactor had the largest ammonium, nitrite, and total nitrogen removal efficiency achieved at 86.4%, 82.9%, and 71.3% 4.1.2 Relationship between nitrogenous components in Anammox process According to Strous et al., the theoretical ratio of the TN removal rate, nitrite removal rate, and nitrate formation rate to the ammonium removal rate was determined to be 2.06:1.32:0.26 The experimental results show the correlation relationship between the TN removal rate, nitrite removal rate, and nitrate formation rate with the ammonium removal rate in experimental periods, shown in Fig 4.5 Period Period Period Period Fig 4.5 Correlation between nitrogen components in the periods of Anammox process The results in Fig 4.5 show that the correlation between the total nitrogen removal rate, the nitrite removal rate, and the nitrate formation rate in periods and is closer to the theory than in periods and It can be explained by the fact that Planctomycetes in periods 3, and have had enough time to adapt and develop stably compared to periods and 4.1.3 Results, discussion, and comparison of research results evaluating nitrogen removal efficiency in AX reactor using Felibendy carrier with some other studies Research on nitrogen treatment by Anammox process with a fixed bed biomass carrier (Felibendy) was conducted to compare with the results of some other studies using high PVA gel, MC, PE… The different treatment efficiency and NRR in the studies may be due to the nature of different biomass carriers 4.2 Research content Evaluation of nitrogen removal efficiency in domestic wastewater by partial nitrification and Anammox process 4.2.1 The conversion of ammonium to nitrite in the PN reactor The PN reactor using real domestic wastewater from the septic tank is conducted in periods Fig 4.6 Changes of nitrogenous compounds in the PN reactor The PN reactor implements the partial conversion of ammonium to nitrite (nitrite/ammonium ratio of approximately 1:1 is suitable for following the anammox process) This nitrite/ammonium ratio depends on many operating factors, including HRT Experimental results have shown that the HRT of 9h in the PN reactor is suitable enough for the Nitrosomonas bacteria to carry out the process to generate the necessary nitrite/ammonium ratio for the Anammox process 4.2.2 Changes of ammonium, nitrite, and total nitrogen concentrations in the AX reactor The partial nitrification process's effluent is pumped into the AX reactor to carry out the Anammox process The variation of concentrations of nitrogenous compounds in the AX reactor during the period is shown in Fig 4.7 Fig 4.7 Changes of nitrogenous compounds concentrations in the AX reactor Fig 4.8 Changes of TN concentration and TN removal efficiency in the AX reactor When the HRT was reduced to 4.5h (period 2c), the ammonium removal efficiency also decreased sharply; the effluent quality exceeded the requirements of the receiving source (ammonium concentration >10 mg/L) The research determined that the AX reactor's minimum HRT is hours, which is enough for Planctomycetes bacteria to carry out ammonium metabolism 4.2.3 Nitrogen treatment efficiency of the PN/AX systems Fig 4.9 Changes of ammonium and TN concentration in the PN/AX system After 210 days of the experiment, the ammonium and total nitrogen removal efficiency of the PN/AX system reached 91.4% and 69.8%, respectively The output wastewater quality meets the requirements according to QCVN 14:2008/BTNMT (column B) 4.2.4 Results of gene sequencing of bacteria on carrier The determination of the bacterial community on the carrier is aimed at confirming that the operating conditions of the model are consistent with the existence of Planctomycetes bacteria when nitrogen treatment is carried out in real domestic wastewater 4.2.5 Kinetic equations of partial nitrification and Anammox process This study has determined that the Stover-Kincannon model is the most suitable and can be applied to use a kinetic model to predict the substrate concentration in wastewater and treatment efficiency under similar operating conditions 4.2.6 Results, discussion, and comparison with other studies The study was conducted to evaluate the efficiency of actual domestic wastewater treatment on the PN/AX model system The total nitrogen removal efficiency in the experiment reached 69.78%, equivalent to some other studies, such as the study of Nguyen Nhu Hien [8] (65%) or Xiao [132] (73%), even higher than the study of Strous [102] with only 36.36% and Pham Khac Lieu [71] (56.3%) The efficiency of the ammonium removal process in this experiment reached 91.4%, which was also higher than in some other experiments 4.3 Evaluation of the influence of organic matter content on Anammox process for nitrogen treatment 4.3.1 Changes of concentrations and treatment efficiency of nitrogenous compounds over periods of study The efficiency of nitrogen removal in wastewater was affected by the presence of organic matter The treatment efficiency decreased when the concentration of organic matter in the wastewater (or the C/N ratio) increased The research determined that with COD > 300 mg/L, the output ammonium concentration did not meet the requirements of QCVN 14:2008 (column B) Average NH +4-N concentration in effluent 15 C On ce 10 ntr ati on (m g/l HRT=6h 23.55.5 C/N ratios HRT=9h Average NO -2-N concentration in effluent 123.5 5.56 C/N ratios HRT=6hHRT=9hHRT=12h HRT=12h 30 Average TN concentration in effluent 25 Co 20 nc 15 ent 10 rat io n Average NO3 - -N concentration in effluent 10 Co nc en tra tio n (m g/l 10 Co nc ent rat io n (m g/l (m g/l 23.5 5.56 C/N ratios 01 123.55.567 C/N ratios HRT=6hHRT=9hHRT=12h HRT=6hHRT=9hHRT=12h Fig 4.10 Changes of nitrogen concentrations according to HRT and C/N ratios 80 Re 70 m ov al 60 eff ici en 50 cy (% 40 Ammonium removal efficiency 80 Nitrite removal efficiency Re m ov 75 al eff ici 70 en cy (% 65 123.5 5.56 C/N ratios HRT=6hHRT=9hHRT=12h Nitrate producing efficiency 80 Re m 70 ov al eff 60 ici en cy 50 (% 80 Pr od uc in g e ffi cie nc 75 70 65 01 HRT=6h 23.5 5.56 C/N ratios HRT=9h 01 60 HRT=12h HRT=6h 23.5 5.56 C/N ratios HRT=9h HRT=12h TN removal efficiency 01 40 HRT=6h 23.5 5.56 C/N ratios HRT=9h HRT=12h Fig 4.11 Changes of nitrogen removal efficiency according to HRT and C/N ratios 4.3.2 Stover Kincannon model and kinetic parameters of the Anammox process for different C/N ratios The study also determined the maximum consumption rate (Umax) and the saturation constant (KB) of the Anammox process corresponding to different C/N ratios Table 4.1 The kinetic parameter U max, and KB according to the StoverKincannon model for different C/N ratios + TN NH4 -N C/N Umax KB Umax KB ratios R2 R2 0,685 0,846 0,998 0,982 1,427 0,998 1,0 0,535 0,661 0,999 0,853 1,253 0,998 2,0 0,480 0,617 0,997 0,759 1,137 0,996 3,5 0,430 0,584 0,998 0,714 1,112 0,998 5,5 0,339 0,515 0,997 0,628 1,045 0,998 6,0 0,314 0,498 0,997 0,599 1,022 0,996 The concentration of effluent: 𝑆=𝑆 𝑆 𝑆𝑆𝑆 − 𝑆0 𝑆 (4.1) 𝑆 𝑆𝑆+ 𝑆𝑆𝑆0 The efficiency of treatment: 𝑆𝑆𝑆𝑆 𝑆𝑆𝑆 = 𝑆 𝑆𝑆 + 𝑆𝑆𝑆 (4.2) 4.3.3 Discussion and comparison of research results evaluating the influence of organic matter content on the Anammox process with some other studies The study determined that with a concentration of organic matter in wastewater greater than 300 mg/L, the treatment efficiency of the Anammox process decreased suddenly This study's results are similar to those of some other studies The high concentration of organic matter (or high C/N ratio) will inhibit the Planctomycetes bacteria, so the Anammox process will not be effective Therefore, the application scope of the Anammox process is to treat nitrogen in domestic wastewater of the fixed bed reactor using a fixed bed biomass carrier (Felibendy) when COD < 300mg/L For domestic wastewater with high COD, the organic matter must be partly removed (reduced COD below 300 mg/L) before applying the Anammox process CONCLUSION CONCLUSION The dissertation has evaluated the applicability of the Anammox process using a fixed bed biomass carrier (Felibendy) to treat nitrogenous compounds in domestic wastewater and has the following conclusions: The total nitrogen removal rate in the AX reactor increased gradually with each period and reached the maximum value of 1.15 kg N/m3/d at the end of phase (HRT=6h) The Felibendy carrier is capable of storing Planctomycetes bacteria, which is suitable as a carrier for the Anammox process in the AX reactor The removal efficiency of ammonium, nitrite and total nitrogen in the AX reactor using a fixed bed biomass carrier (Felibendy) after 191 days of operation reached the highest values of 86.4%, 82.9%, and 71.5%, respectively The PN/AX system (partial nitrification reactor and Anammox reactor) has been able to remove nitrogenous compounds in domestic wastewater, ensuring the requirements according to column B of QCVN 14:2008/BTNMT with ammonium and total nitrogen treatment efficiency reached 91.4 ± 0.2 % and 69.8 ± 0.7% With the hydraulic retention time of hours in the PN reactor, the ammonium/nitrite ratio in the wastewater is 1.03 ± 0.02, suitable for the conditions following the Anammox process For the AX reactor, the HRT of hours to ensure the effluent ammonium concentration of 9.9±0.3 mg/L, which meets the requirements of the wastewater receiving source The research has determined that the suitable HRT for the partial nitrification process (PN reactor) is hours and for the Anammox process (AX reactor) is hours The research has determined that among kinetics models (the first order, the Grau, and the Stover Kincannon), the Stover Kincannon model is the most suitable to describe the partial nitrification process in the PN reactor and the Anammox process in AX reactor In the PN reactor, the researchers determined that the saturation constant K B for ammonium and nitrite substrates is 8.038 and 0.905 (mg/L/d), respectively; The maximum substrate consumption constant U max for ammonium and nitrite is 15,489 and 1,156 (mg/L/d), respectively In the AX reactor with wastewater after the PN reactor, the research determined KB and Umax of the Stover Kincannon model for ammonium substrate is K B = 1.7389 (mg/L/d); Umax = 1.2411 (mg/L/d) and for TN substrate is K B = 3.083 (mg/L/d); Umax = 1,763 (mg/L/d) The research shows that high organic matter concentration (COD) in domestic wastewater influences the efficiency of the Anammox process The inhibition threshold for the Anammox process in the AX reactor using a fixed bed biomass carrier was determined to be 300 mg/L The dissertation also determined the maximum consumption rate constant (Umax) and the saturation constant (KB) of the Anammox process are inversely proportional to the C/N ratio in the wastewater For ammonium removal, when the C/N ratios increases from to 6.0, the Umax gradually decreases from 0.685 to 0.314 (mg/L/d); the KB decreased from 0.846 to 0.498 (mg/L/d) Similarly, with TN removal process, when the C/N ratio increased from to 6.0, the Umax gradually decreased from 0.982 to 0.599 (mg/L/d) and the KB gradually decreased from 0.982 to 0.599 (mg/L/d) 1,427 down to 1,022 (mg/L/d) RECOMMENDATION To continue studying and surveying the other influencing factors and finding solutions for overcoming the effects of high COD to have a promising technology for treating domestic/urban wastewater using the Anammox process To continue studying and using PN/AX systems with Felibendy carrier at pilot scale and full scale to evaluate energy consumption and economic efficiency of nitrogenous compounds treatment solution in domestic wastewater/urban wastewater using the Anammox process To research and evaluate optimal growth and development conditions of bacteria and culture and enrichment of Nitrosomonas and Planctomycetes bacteria LIST OF AUTHOR'S PUBLISHED ARTICLES RELATED TO THE DISSERTATION Nguyen Thị Mỹ Hạnh (2016), “Application of Anammox process to treat ammonium in wastewater”, Science Journal of Architecture and Construction, ISSN 1859-350X, 21, 57-61 Nguyen Thi My Hanh, Tran Thi Hien Hoa (2019), “Evaluation of nitrogen removal efficiency in domestic wastewater using partial nitrification and Anammox process”, Science Journal of Architecture and Construction, ISSN 1859-350X, 34, 43-46 Nguyen Thi My Hanh, Tran Thi Hien Hoa (2020), “Effect of hydraulic retention time on nitrogen removal in domestic wastewater by partial nitritation and Anammox processes”, Journal of Science and Technology in Civil Engineering (STCE)-NUCE, 14(2), 127-136 ISSN 1859-2996, https://doi.org/10.31814/stce.nuce2020-14(2)-12 Hanh Thi My Nguyen, & Hoa Thi Hien Tran (2021), “Effect of organic matter on nitrogen removal through the anammox process”, Water Environment Research, 93(4), 608-619, https://doi.org/10.1002/wer ... Literature review of nitrogen treatment technology in domestic wastewater, literature review of Anammox process in the world and Vietnam, literature review of biomass carrier used in Anammox process... University of Civil Engineering Scientific Advisor: Assoc.Prof PhD Tran Thi Hien Hoa Reviewer 1: Assoc.Prof PhD Nguyen Manh Khai Reviewer 2: Assoc.Prof PhD Hoang Thi Thu Huong Reviewer 3: Assoc.Prof... studies on the Anammox process in Vietnam are still limited 1.4.2 Literature review of some carriers using for the Anammox process Many carriers have been studied and applied to the Anammox process,